1. Field of the Invention
The present invention relates to a cartridge for containing a photosensitive recording medium, and in particular relates to improvement of light shielding performance and dustproof performance of interspace formed between a cartridge body and a shutter, which constitute a cartridge for containing a hologram recording medium being as the photosensitive recording medium.
2. Description of the Related Art
A hologram recording medium for recording data by means of a hologram is invented (see Japanese Patent-Laid Open Publication No. 2004-029476, for instance). The hologram recording medium is a photosensitive recording medium comprising a hologram recording layer, which is made of a photosensitive material and is formed on a disk-shaped support. By recording the data in multi layers as interference fringes of a laser beam, it is possible to obtain larger capacity of data storage in comparison with a DVD, which is a conventionally prevailing recording medium. As to this hologram recording medium, performance thereof is adversely affected when the hologram recording layer is exposed to the light and when dust adheres thereto. Thus, the hologram recording medium is contained in a cartridge having light shielding properties and dustproof properties when treated (see Japanese Patent Laid-Open Publication No. 2003-317422, for instance).
In the invention described in the above-noted Publication No. 2004-029476, the hologram recording medium is contained in a cartridge similar to a DVD-RAM cartridge. This cartridge is made of a material having small light transmittance relative to a wavelength region wherein the hologram recording layer is affected. Meanwhile, in the invention described in the above-noted Publication No. 2003-317422, the cartridge is made of a material by which the light having a sensitive color of the hologram recording layer is shielded. Further, a sponge-like light-shielding material is applied to a joint of movable portions, which is for exposing the hologram recording medium to the outside.
If the cartridge described in the Publication No. 2004-029476 has a general structure for containing a disk-shaped recording medium, it is considered that this cartridge comprises an upper shell, a lower shell, openings and a shutter. The upper and lower shells contain the recording medium so as to interpose this medium in a rotatable manner. The openings are formed in the upper and lower shells so as to expose a part of the recording medium to the outside. The shutter opens and closes the opening. By the way, in case of the cartridge containing the hologram recording medium, if interspace formed between a cartridge body and a shutter is not properly shaded and sealed, light and dust enter the cartridge to adversely affect the hologram recording medium. Although the cartridge described in the Publication No. 2004-029476 uses the material having the small light transmittance, there is no description regarding a light shielding structure and a dustproof structure of the interspace formed between the cartridge body and the shutter.
As to the cartridge described in the above-noted Publication No. 2003-317422, the interspace formed between the cartridge body and the shutter is shaded with a sponge-like light-shielding material. However, in case the light-shielding material peels or deteriorates, there arises a problem in that light and dust are prevented from being effectively shut out.